The invention relates to a method of purifying industrial sugar solutions by the adsorption of the non-sugar substances at ion exchangers, especially at cation exchangers employing calcium.
Industrial sugar solutions, for instance, molasses, are usually obtained as the final run during the production of sugar from sugar beets and sugar cane. Molasses contain, in the known composition, non-sugar substances, which prevent a crystallizaton of the sugar out of the molasses and which must be separated when it is desired to extract the sugar from the molasses in its crystalline form.
It is already known to separate the non-sugar substances by ion exchange with the aid of weakly cross-linked cation exchangers in the alkaline form, (German patent publication DT-OS 22 32 093).
There are also known methods by which industrial sugar solutions are separated into sugar substances and non-sugar substances by means of fluid-distribution chromatography at cation exchangers using calcium (German patent publication DT-AS 23 62 211, DT-AS 25 18 284).
A considerable disadvantage of the known methods resides in the heavy dilution of the solutions during the passage through the separating columns. At the direction of flow from above to below, which is required for these methods, and at the necessary huge column diameters, irregularities in the flow during the passage through the columns cannot be avoided. The flow conditions are further disadvantageously influenced by the alternate swelling and shrinking of the resins and by the high input concentration of the starting solutions to be purified. The consequences of this are a strong mixing of the solutions with the fore-running and the aft-running water and a correspondingly minute concentration of the sugar fraction and of the non-sugar fraction.
The sugar fraction and of the non-sugar fraction requires a considerable expenditure for the concentration necessary during the further treatment, both with respect to the costs of installations as well as the continuous energy expenses. The latter constitute a substantial part of the operating costs of these methods.
At low concentrations, the adsorption capacity of the resins is furthermore utilized only to a very limited extent. This makes it necessary to utilize huge resin amounts, with correspondingly high installation costs; a further drawback is the difficulties generally encountered when operating large columns.